Question : Some of the importantfossils which have been studied are those of organismsX, Y and Z. X were marine arthropodswhich were commonbetween 400 to 600 million years ago. Y were the invertebrate animals (molluscs)with a flat, coiled, spiralshell which lived in the sea about 180 million years ago. Z are the extinct carnivorousor herbivorous reptiles which appeared on the earth about 250 million years ago and became extinct about 65 million years ago. What are X, Y and Z ?

Question : Some of the importantfossils which have been studied are th

1.	Question : Some of the importantfossils which have been studied are those of organismsX, Y and Z. X were marine arthropodswhich were commonbetween 400 to 600 million years ago. Y were the invertebrate animals (molluscs)with a flat, coiled, spiralshell which lived in the sea about 180 million years ago. Z are the extinct carnivorousor herbivorous reptiles which appeared on the earth about 250 million years ago and became extinct about 65 million years ago. What are X, Y and Z ?
Answer» ANSWER :X : TRILOBITES ; Y : Ammonites ; Z : Dinosaurs